Field of the Invention
The present invention relates to a metamaterial structure formed in a pattern on a printed circuit board.
Description of the Related Art
In recent years, attention has been placed on research in metamaterial technology. The use of metamaterial technology makes it possible to construct materials having properties that do not exist in nature and have never been achievable before. Review has been underway for the application of metamaterial technology to electromagnetic bandgap structures (referred to hereinafter as “EBG structures”), structures having effects similar to a magnetic wall, antenna elements, structures for improving antenna characteristics (radiation pattern, etc.), RF devices, and the like.
For example, an EBG structure has been proposed as a method of preventing electromagnetic interference between electronic components and circuits (e.g., see Japanese Patent Laid-Open No. 2011-040703). Technology has also been disclosed for reducing the thickness and size of an antenna by using the characteristics of an EBG structure to suppress mutual interference between antennas and causing the EBG structure to function as a magnetic wall as well (e.g., Japanese Patent Laid-Open No. 2012-65371). There has also been a proposal regarding an antenna that utilizes a metamaterial structure (e.g., Japanese Patent Laid-Open No. 2010-502131). Furthermore, there has been a proposal regarding a method of reducing surface current induced on the ground plate by an antenna (e.g., Japanese Patent Laid-Open No. 2002-510886). Moreover, there has been a proposal for a configuration in which a capacitance forming conductor is provided in the configuration proposed in Japanese Patent Laid-Open No. 2002-510886 (e.g., Japanese Patent Laid-Open No. 2010-16554).
Conventionally, there has been a proposal for a method of arranging metamaterial cells in a direction perpendicular to a surface of the ground plate, and there has also been a proposal regarding technology for reducing the size of such cells. There has also been a proposal regarding a method of constructing an EBG structure in the periphery of the ground plate of a circuit board. However, there has been a problem of the inability to realize a sufficient reduction in size with conventional technology.